The invention relates to an apparatus for opening a signature or printed sheet and depositing it on a transporting device, the apparatus comprising a continuously rotating gripper cylinder, as well as a first and a second opening cylinder arranged below the gripper cylinder, the shafts of which extend substantially parallel to the gripper cylinder shaft. These opening cylinders respectively open one signature and deposit it with the opened side facing downward onto the transporting device, wherein the first opening cylinder engages with a section of its circumference in the region of rotation for the gripper cylinder to grip a signature on the side to be opened, such that it can be released again.
An apparatus of this type is disclosed, inter alia, in Swiss patent document CH 408 065. This apparatus, called a depositing machine therein, functions to remove signatures from a stack and transfer them from the continuously rotating gripper cylinder to opening cylinders, which open the signatures and deposit them onto a circulating transporting device, wherein this transporting device can be a gathering chain which is known per se.
A different apparatus of the aforementioned type is disclosed in Swiss patent document CH 652 103 A. With this apparatus, one opening cylinder is driven with a peripheral speed that is periodically accelerated above and/or delayed below its mean speed. The first opening cylinder passes with a peripheral section and increased speed through the peripheral region of the gripper cylinder and is subsequently delayed, so that the downward speed of the signature reaches a minimum. This is intended to achieve a further increase in the processing. However, this apparatus has the disadvantage that the drive elements are subjected to comparably high wear as a result of the changing loads on the drive. A further disadvantage is that the suction elements of the opening cylinders impact at maximum lag speed with the signatures, thus making it considerably more difficult to maintain the functional safety of the suction opening. Finally, as a result of the delay in the drop speed, large-format signatures cannot be deposited without problems.